Embodiments found within the prior art generally utilize handshaking between conveyor segments (aka zones) as disclosed in U.S. Pat. Nos. 5,862,907; 6,860,381; 7,905,345; 6,035,999; 6,244,421; 6,253,906. These embodiments use a single relay logic contact signal that is sent from a conveyor segment “n” to an upstream segment relay logic gate. This single on/off bit signal state is either “clear-to-send” when zone “n” is empty and ready to accept an article from zone “n−1”, or else it is an “inhibit” state to prevent an article from being released by “n−1” because “n” is not clear and ready.
If and when the direction of article flow is reversed, a second relay logic contact signal is required, in the opposite direction (from segment “n−1” to “n”) to serve a similar flow control function.
Additionally, or instead, a direct fieldbus network interface connection (NIC) may be provided to connect each drive (motor controller) of a segment or group of segments sharing a drive, such as found in the disclosures of U.S. Pat. Nos. 8,587,245; 8,248,009; 5,955,859; and U.S. Pat. App. No. 2005/0094343.
Importantly, the prior art does not disclose segments that “talk to each other” intelligently in order to pass more than a single on/off inhibit bit of information from one segment to the next. In the latter case, the fieldbus can carry broader information content, but it is not being used for peer-to-peer exchange of data among neighboring segments, but rather only for separately reporting to a common supervisory PLC. In the former case, the peer-to-peer exchange is only of a single state like a stop light.
In a third variation, as disclosed in U.S. Pat. Nos. 7,996,104; 5,771,174; 8,761,937; 8,885,516; U.S. Pat. App. No. 2002/0107582; and EP 2511780, each drive's NIC can directly address messages to its peer neighbors, providing a mechanism to support many schemes of article traffic control communications. However, no actual inter-zone communication scheme for embedding conveyor article routing control has been described in these or any other known disclosures.
Furthermore, the use of paper “traveler” routing slips to accompany conveyed articles of work-in-progress is common in factories worldwide but no electronic equivalent, carried by peer-to-peer messages on a serial or fieldbus network, has been described in any known disclosure. Reference U.S. Pat. App. Nos. 2006/0041628; 2010/0036522; and U.S. Pat. Nos. 6,470,227; 8,069,071.
Therefore, there is a need for an electronic peer-to-peer message serving as a “traveler” or “routing slip” for conveyor routing control, whether carried on a serial or a fieldbus or other network connection, whether public or private.